Multiplex-telegraph circuit.



UNITED STATES LAVRENOE A. MCCARTHY,

P T NT OFFICE.

OF BROOKLYN, NElV YORK.

MULTIPLEX-TELEGRAP H CIRCUIT.

SPECIFICATION forming part of Letters Patent No. 700,800, dated May 27,1902. Application filed November 18, 1901. Serial No. 82,712. (Nomodel.)

To all whom it may concern:

Be it known that I, LAWRENCE A. MCCAR- THY,a citizen of the UnitedStates of America, residing at 1059 Bedford avenue, Brooklyn, New York,have inventednew and useful Improvements in Multiplex-TelegraphCircuits, of which the following is a specification.

The objectof this invention is to combine with the receiving instrumentsand controlling device at the one end of a quadruplextelegraph circuit,as shown in Patent No. 693,530, allowed me February 18, 1902,shunting-magnets, so arranged that the incoming current from the distantend of the circuit will not be able to interfere with or change theresistance of the artificial line, and thereby throw the receivinginstruments out of balance and cause them to record false or mutilatedsignals.

I attain the object of my invention by the combining with thecontrolling and receiving instruments in the main and artificial line atthe home station of a non-polarized electromagnet having a singlewinding the separated coils of which are inserted one in the main andthe other in the artificial line and are arranged to act in an oppositedirectionon an armature common to both, drawing said armature to eitherthe one side or to the other side,pr'essing one or the other of thecontact-arms away from the central contact-stop, thereby breaking andkeeping open the local circuit on the controlling instrument as long asone of the magnets of the shunting -'relay is enough stronger than theother magnet to overcome the retractile springs, which are adjusted to aprearranged strength,as hereinafter set forth.

Referring to the accompanying drawings, which are made a part of thisspecification, Figure 1 gives a general outline of the arrangement andconnections of the receiving and controlling instruments in the main andartificial line and the local circuit of the con trolling instrument atthe one end of a cir cuit and shows a dynamo or source of power at theother or distant end of the circuit. Fig. 2 gives a side view of amodified form of the controlling instrument, a top view of the rheostat,a battery or source of power, and an electromagnet in therheostat-circuit arranged to'polarize or reverse the polarity of theneedle as the polarity ofthe coils of the controlling instrument ischanged by a reversal of current through them from the home battery, andthus compelling the needle to be always drawn toward the strongercoil'irrespective of the changes in the polarity of the current passingthrough them from the home battery. Fig. 2 also shows localcontact-stops ,to the needle, a local circuit between said needle andcontact-stops, and a local battery and magnets in said local circuit.

Again referring to Fig. 1 and starting atM B, the main battery N R is aneutral relay, P R a polarized relay.

S R S R are the magnets of a shunting-relay having a single winding,magnet S R loeing connected in the main-lineside of the circuit andmagnet S R connected in the rheostat or artificial-line side.

S is a non-polarized armature pivoted to' swing between and common toboth magnets S R and S R, the free end of said armature extendingbetween the free ends of contactarms h h.

h and h are contact-arms trunnioned at i.

l is a limit or contact post, against. which contact-arms hand h rest.

j and jareadjustable springs arranged to draw or press contact-arms handh toward each. other and against the limit or contact stopl, andthuscomplete the local circuit shown from needle or through contact-armh, stop Z, and contact-arm h to and through local battery L B and localmagnet m or m to stop 3 or s. v

W represents condensers attached to the artificial linethrough theadjustable resistance v,-and R represents an automatic rheostaf.(Covered by patent previously referred to.

In Fig. 2 the current is shown as passing from one pole of the mainbatteryMB through coil 0 to the main line and through coil 0, magnet K,and rheostat R to ground at G. The needle 01 is shown pivoted to one endof the core of magnet K at t and'is thereby magnetized by said magnet.Therefore if opposite magnetic poles are'presented to each other and toneedle n' by coils O and C by reversing the poles ofmagnet K and needleat every time the current is reversed through the coils by the homebattery needle 'n' will be compelledto pull always toward the shorterand thereby the stronger side instead of swinging from sideto side oneach reversal of the current through said coils, as would be the casewere the needle permanently magnetized. Now assuming that retractilesprings j and j (shown in Fig. l) have been adjusted so thatcontact-arms h and h cannot be drawn away from post Z by less than anexcess of one-fourth of the full strength of the main battery passingthrough one side more than through the other side of the circuit theaction of different currents passing through the magnets S R and S R ofthe shunting-relay and through coils O and O" of the controllinginstrument and their action with or on each other and on the rheostat orartificial line is substantiallyasfollows: Withthedistantend of the mainline to ground the current from the home battery would divide, going tothe line on the one side and to the ground through the rheostat on theother side, and if the resistance in the rheostat equaled the resistanceof the main line the current from the battery would divide equallythrough each side and have equal effect on armature so or needle N; butif the line had, say, a resistance of three thousand five hundred ohmsand the rheostat a resistance of four thousand ohms there would morecurrent go through the main line than through the artificial line, andwhile this difference in strengthof current would not be great enough toenable shunting- -inagnet S R to attract armature S with suffi- ,;the'local circuit.

cient strength to cause it to overcome spring j and press contact-arm h.away from post Z it would be great enough to cause mutilated signals bythe receiving instruments and would also be great enough to cause coil 0of the controlling instru ment to attract the lower end of needlen andcausing its upper end to swing against stops, closing the local circuitthrough m and cause rheostat R to act and its resistance to be changeduntil it equaled the resistance of the line, when coils C and 0, havingregained equal strength, would have an equal attractive power overneedle 11 and draw it again to a central position and break Now withboth branches of the circuit of equal resistance if a positive currentof a certain strength be sent to line from the home battery and anegative current of equal strength be sent to line from the distantstation the effect would be to double the attractive power of magnet S Rand coil C, causing armature S to be strongly drawn against arm 71,pressing it away from stop Z and open the local circuit shown fromneedle n through arm h, stop Z, arm it, local battery L B, and magnet mto stop sand preventing needle 01 from closing said circuit by beingdrawn against stop 8, and thus preventing rheostat R from being actuatedand the resistance in the artificial line from being changed or with thepositive current from the home battery remaining to line and the currentat the distant end being reversed, sending a current of positivepolarity to line,

the result would be to neutralize the magnetizing effect of each otheron magnet S R and allow magnet S R to attract armature sa and,

as long as a current is sent from the distant station the effect will beto cause magnet S R or S R to act on armature sot, causing it in turn toact against contact-arms h or h and prevent coils G O and needle n frombeing able to have any eitect on or control over magnets m or m andthrough them on automatic rheostat R; but as soon as the battery istaken off at theudistant end and the'wire put to ground the home batterysplits through magnets S R and S R andcoils C and O, causing coil C or Cto act on needle 11 and through it on magnets m or m up to a dif ferenceof resistance in the main and art1ficial line equal to the strength atwhich retractile springs j andj' have been set, which would normally beone-fourth of the strength of the main battery, as that is the lowestdivision of battery made in quadruplex circuits, and as the differenceof resistance at which mutilated signals are caused is much less thanthis equivalent there is quite a wide margin between the resistance atwhich coils O O would be able to act on rheostat R and the resistance atwhich magnets S R S R would prevent them from acting by causing armatureset to break the local circuit controlled by needle 91. It can thereforebe seen that it is possible for a person at one end of a circuit tobalance the instruments at the other end of the circuit by merelycutting off his own battery and putting the wire to ground, thus savingmuch valuable time and preventing annoying delays.

Now, having described the action of the different parts on or with eachother, what I claim as new, and desire to secure by Letters Patent, is

1. In a multiplex-telegraph circuit,the combination of a shuntinginstrument, consisting of electromagnets, an armature, common to saidmagnets, contact-arms, a contact-post, separating the latter, and theadjustable springs, cooperating with said contact-arms,

with the controlling instrument and its local circuit, and meansactuated by said local circuit, for varying the resistance of theartificial line, substantially as set forth.,

2. In a multiplex-telegraph circuit,the combination of ashuntinginstrument, consisting of electromagnets, an armature, common to saidmagnets, the contact-arms, a contactpost, separating the latter, and theadjustable springs, cooperating with said contactarms, with thecontrolling instrument and its local circuit,'and the main andartificial line, and means actuated by said controlling instrument, forvarying the resistance of the artificial line.

3. In a multiplex-telegraph circuit,the comof electromagnets, anarmature, common to said magnets, contact-arms, contact-post, andadjustable springs, with the controlling instrument, its local circuit,the local magnets, in said local circuit, and the automatic rheostat,all substantially as and for the purpose set forth.

4. In a multiplex-telegraph circuit,the combination of a shuntinginstrument, consisting of electromagnets, an armature, common to saidmagnets, the contact-arms, a post, separating the latter, and theadjustable springs, cooperating with said contact-arms, with thecontrolling instrument and its local circuit, the main battery, thereceiving instruments, the main and artificial line and condensers, andmeans in said artificial line, operated by said controlling instrumentfor varying the resistance of the artificial line, substantially assetforth.

5. In a multiplex-telegraph circuit,the com bination of a controllinginstrument, having coils of wire, a needle, common tosaid coils andpivoted to an electromagnet, local contact-stops, for said needle; andsaid magnet, connected in the artificial line, with the local circuit,the local magnets, in said circuit, the main battery, the main andartificial line, and means in said artificial line for so adjusting theresistance of the latter, that the resistance of the main line andartificial line are always equal, all substantially as and for thepurpose set forth.

LAWRENCE A. MCCARTHY.

Witnesses:

O. R. DANFORTH, M. MCCARTHY.

